Starting service using ttyUSB0 on boot

Installing and Using OpenWrt
1

I have a modbus USB adapter to read power usage data. I created an init.d procd script and when starting it via web-interface or manually via cli it works fine. I just can't get it to run automatically after boot. Directly after boot the status is "inactive". I have a "boot()" function in the script which is triggered correctly. I have a logger call in there and the boot function finishes and does what it is supposed to. I also have a logger call at the top of "start_service()" which is not triggered on boot. I have a "procd_set_param netdev /dev/ttyUSB0" line in case the USB adapter is re-plugged. I also have "procd_set_param respawn 10 1 0" which is supposed to retry indefinitely.

As a workaround I also added a script in /etc/hotplug.d/tty with just debugging output, but it is only triggered on re-plugging, not boot.

I don't know how to proceed further. I found nothing in the logs indicating why the script isn't triggered and I don't understand why hotplug.d isn't triggering after boot.

2

post the script along with the output of ubus call system board.

3 
#!/bin/sh /etc/rc.common

START=99
USE_PROCD=1
PROCD_DEBUG=1

boot() {
        logger "Creating strom_fifo"
        [ -e /tmp/strom_fifo ] || /usr/bin/mkfifo /tmp/strom_fifo
}

start_service() {
        logger "Starting strom"
        procd_open_instance
        procd_set_param respawn 10 1 0
        procd_set_param netdev /dev/ttyUSB0
        procd_set_param stderr 1
        procd_set_param pidfile /var/run/strom.pid
        procd_set_param command /usr/bin/lua /root/readpm.lua /dev/ttyUSB0
        procd_close_instance
}

{
	"kernel": "6.6.86",
	"hostname": "OpenWrt",
	"system": "Atheros AR9344 rev 2",
	"model": "TP-Link TL-WDR3600 v1",
	"board_name": "tplink,tl-wdr3600-v1",
	"rootfs_type": "squashfs",
	"release": {
		"distribution": "OpenWrt",
		"version": "24.10.1",
		"revision": "r28597-0425664679",
		"target": "ath79/generic",
		"description": "OpenWrt 24.10.1 r28597-0425664679",
		"builddate": "1744562312"
	}
}
4

Another reason for the hotplug script I tried was to create a symlink for the correct device in case I will add another one. As I wrote the hotplug script doesn't trigger on boot either.

set -eu
logger -t hotplug $(env)
logger -t hotplug "strom ${ACTION:-} ${DEVNAME:-} ${DEVPATH:-} ${MAJOR:-} ${MINOR:-} ${SUBSYSTEM:-}"